Means for measuring volt amperes



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Int/'en f i v L. A. PAINE MEANS FORv MEASURING-VOLT AMPERES '3Sheets-#Sheet' Fild `Jmpl'r., 1925 z Inventor Nam 22s wif/2 l L. A.PAINE MEANS FOR MEASURING VOLT AMPERES Filed Jan. 17, 1925 5Sheets-Sheet 3 A fi Ml TK IV B LU;

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Patentes Nov. 2z, 192?.

urrso sitA'rEs PATENT oFF-ics;

f LOUIS A. PAINE, OF TORONTO, ONTARIO, CANADA, ASSIG'NOR T0' THE LINCOLNMETER COMPANY, LIMITED, OF TORONTO, CANADA.,

MEANS,y FOR MEASURING VOLT AMPERES.

4 Application led. January 17, 1923. Serial No. 613,238.

The principal objects of thisjinvention are to devise a practical methodof utilizing standard watt meters or watt hour meters 'for measuringvolt amperes or volt ampere hours and to devise a simple means forshifting the angular phase position of an alternating voltage or currentand further to enable the use of a low voltage meter on a high tensioncircuit,

A further important object is to devise a simple means for controllingphase position automatically by power factor.

The principal feature of the invention consists in effecting a. shift inthe angular phase position of voltages or currents in derived circuitsin response to the power fact tor of the load under measurement by meansof a single moving element and a single field, the magnitude of thederived voltage or current being proportional to the applied voltage.

A further important feature consists in effecting the shift of circuitconnections or iniue'nces by utilizing a power factor meter which willautomatically assume an angular position to produce a maximum magneticAflux through the joint iniiuence of both current and voltage excitedwindings.

In the drawings Figure 1 is a diagram illustrating a method of carryingthisfinvention into effect, inl which the phase position of a 3 phasealternating voltage is auto- A matically controlled by power factor.

Figure 1 is a diagram illustrating` the practical application of thetransformer circuits illustrated in Figure 1.

Figure 2 is a diagram of the preferred form of power factor meter.

Figure 3 is a diagram illustrating the principles involved in the metershown in Figure 2.

Figure 4 is 'a diagram illustrating the application of the meter shownin Figure 2 to the measurement of volt amperes in a 3 phase circuit.

`|Figure 5 is a diagram illustrating the angular phase relation betweencurrents and voltages in a normal 3 phase circuit.

Figure 6 is a. diagram illustrating the application of the method ofmeasurement in a 2 phase circuit.

Figure 7 is a diagram illustrating the application of the phase shiftingpower factor meter to a thermalvdemandwatt meter for' Figure 9 is adiagram illustrating thev method of correcting for'rotational torque, asan induction motor.

, Referringto Figures 1 and 1a, am and ay are the primary windings oftwo single phase voltage transformers connected to the 3 phase circuitABC and indicated'in their relative phase positions in Figure 1. Thesecondaries of these transformers may be connected to any standard wattmeter or watt hour meter as shown in Fig. 1L if it be desired to measurethe volt amperes or volt ampere hours of the` circuit ABC.

On the same 'core as the winding am is placed an auxiliary winding 64eand on the core with ay is placed an auxiliary winding 022. The numberof turns in the Winding ,714 is the same as the winding 02e and theturns in the' windings 642 equal those in the winding aeg. Thereforewhen a 3 phase voltage is applied' to the transformer terminals ab@ thequadrilateral 1124 .202 represents, both in magnitude and phase positionthe voltages that will be ydeveloped in the` windings described. Itobvious that if the values (L64 and a0, be properly chosen andw propertap points be brought out from the transformer coils, it will bepossible to shift the relative phase position of the secondaries oncores am and afz/ by any desired amount by applying the circuit voltageto these tap points instead' of to the original terminals abc. Forexample, if the circuit ABC is applied to taps a. 6 c there will resulta phase shift in the secondaries of the transformers aw and ayproportional to the angle ac a or b a y, the taps /being so selectedthat the triangle 1r/'b' c is equal to the triangle abc. Y

It must also be understood that the tap points b4 and c2 are subject tovariation as` well vas the number of turns in the trans@- formerwindings a02, be, L54 and 02e. With these tap points under control aphase shiftz A.

' of any desired degree in either direction may be secured. Thismethodof phase shift illustrated in Figure 1, a switch S is prol-aa-vided with a plurality of groups of contacts which are connected withdifferent arrangei ments of taps.` The switch arm l) pivoted at e isprovided with contacts ABC connected with circuit ABC. Thecontactsindicated by 100 are connected to transformer terminals abc;contacts 95 are connected to transformer taps abc; contacts 80 areconnected to taps az 62 c and contacts 60 are con-v neet-ed to taps@35303. The numerals 100, 95,

80 and 60 represent the power factors atl whicha watt meter willcorrectly read volt amp'eresy in a specific form of this device that hasbeen built, having been demonstrated by actual test. These values differfrom the contiguous values by approximately18 of angular phase shift,consequently the .arrangement shown renders it ,possible to measure thevolt amperesof a circuit with an error of less than 2% over a range ofpower factor fromv 100% l to 43%, but while this Iarrangement is shownfor illustration the method described is applicable toy the measurementof volt amperes by a standard watt meter whether the circuit be laggingor leading and independent of thel amount of lag or lead.`

In the diagram Figure 1et the transformers am and ay correspond to thetransformers i aac' and ay of Fig. 1 as also do the inter-coh- Inections and the `connections to vthe switch S. The values 1GO, 95, 8Oand 60 are given as these have been actually put into practice butobviouslyother values may be chosen y and' additional values `may beused if del sired. Tn Figure. 1 thecurrent windings C1 and@2 ofa-wattmeter are shown connected to transformers T4 and T5, and its voltagewindings V1V and V2 are connected to the secondaries of the transformersam and ay;

`(In order to. effect the shift of the switch S automatically a powerfactor meter is used as illustrated in the diagram Figure 1, the/meter"kF having a stator G provided with poles lh, z' andy'. A rotor lq whoseaxis is at ,e is provided with poles Z, m and a. The stationary polesiz., i vand are excited b currents of the load to 4be measured. der1vedfrom C, B and A through transform-- ers T1', T2, T3', .if desired." rThe'rotor k vis excitedfrom thel voltage'of the circuit un'` dermeasurement. f y l, v f

As is well linowmsuch windings willy/set iueaaaei the magnetic fluxproducedby the joint action of all the magneto motive forces presentwill be-a maximum. The angular position'of the rotor lo will thereforedepend on the power factor of the load under measurement; in otherwords, the structure Fbecomes a power factor meter andmay be 'madesufficiently powerful to operate the switch S shown in Figures 1 and 1a.As shown in Figure 1, both the rotor and the stator Gare wound withpoly'phase windings producing rotating fields in both members. The powerfactor meter will still operate successfully if only one of theselieldsis a. rotating fieldfrand the other a single' phase alternatingfield but making both fields rotating is preferable since correctoperation is still maintained in the event ofl single phase loading andmore accurate operation is lobtained in the case of unbalanced' vloadingin a polyphase circuit.' t must be understood that the directionofmagnetic rotationy is the same if rotating magneto niotive forces are.used on both rotor and stator.

It is also welly known thatin suchv a. power factor meter, stator androtor windings may be interchanged without interfering with` 'successfuloperation of the device'.

The preferred form Yof magnetic circuit for the powerfactor element isshown in Figure 2y which follows the practice` that many years ofexperience have shown is best adapted tothe induction motor, in whichthe problem, in so far as the form of magnetic circuit isjconcerned, issimilar to my power factor meter.' Fig. 2 shows a power factor meteronly, suitable to` substitute for the structurey F in Fig. 1. Additionalfunctions can be obtainedfrom such a structure as is shown in Figures 3,4, 6 and 7 and such functionswill be described later. Referring now toFigure 2, 'G is a laminated iron'stator with 12equally spaced slots S1,S, .,'S3 etc. to Sl2 in y which the windings are placed. Twelve slotsare not essential but this number allows for either 2 phase or 3 phase ywinding. j l The rotor his preferably formed wi-th 13 Islots to receivethe windings, a number prime to the number of stator slots beingprovided' to minimize the tendency to magnetic locking. Other means wellknown in A the artmay also be used to reduce magnetic ,locking orcogging tendency to a negligible quantity. The rotor Ik: is illustratedas ,excited from the voltage of the 3 phase cirl. cuit ABG and thestator-G from the current of ABC through transformers T1, T2, T3 whichproduces, preferably, rotating mag neto motive forces in both rotor andstator. Amtwo pole field is shown as being prefera e. i

In .Figure is shown. an analysis of the magnetic motive forces and -theresulting magnetic fluxes that will 'be produced by the joint action ofthe stator and rotor windf ings pf my power factor meter and alsoindicatin'g some. of the additional functionsl to La inclusiverepresent.this flux at the instant that it becomes a maximum in the WYEdirection. The stator laminations'in which this flux is conducted from Wto l are omitted-also for the sake of clearness. It should beiunderstood, of course, that this magnetic flux rotates, with thefrequency of the applied voltage; i. e., a quarter cycle later than theinstant shown in Figure 3, the flux isa maximumin the NS direction, aquarter cycle still later, a maximum in the FAV direction' (180 from thecondition shown in Figure 3) and a quarter c vcle still later in the SNdirect-ion. That is, the magnetic flux rotates while the windings in.

which the magneto motive forces are produced as well as the' magneticcircuit in which the flux is produced stand still.

If it is assumed that the rotor is free to rotate about the centree eand thata stationary coil P surrounds the rotor and is excited by thecurrent of the circuit under measurement, the coil P will be the seat ofa magneto motive force which will produce an alternating magnetic fluxwhich will flow through the rotor and return as indicated by lines L, toLS. This alternating magneticJ field will remain stationary in space andwill be. maximum. at the instant the current in coil P is a maximum andwill of course alternate with tliecurrent which produces it..

Under the influences of these twofmagneto motive forces, the rotor 7i:(if it be free to more about its axis ce) will assume an angularposition such that the magnetic flux produced b their joint act-ion is amaximum, that. is, the rotor 7c will assume such au angular positionthat. the angular position of the flux produced by the rotating voltage.excited windings on with reference to the plane of P will be the same asth. time-phase of the flux produced by the. stationary current coil P.Other stationary coils connected to the current phases of the circuitABC/army of course be added at the proper angular relation to the coilP.

The principles of thepower factor meter as enunciated in the foregoingare yof course wellknown and they are not claimed as new but it 1S newto use yadditional windings on va structure of this character toproduce' automatic phase shift with power factor.

`Such additional windings are shown and` described later in thisspecification; for instance, the windings occupying slots 2--8 and 6-1'2,of the stator in Figure 4, those occupying slots 1-7 and 4-10 of thestator `in Figure 6 and those occupying slots 3-9 and 5-11 of the.stator in Figure 7. The principle governing the functioning of theseadditional windings is illustrated in Fic. 3. The additional windingsabove-referred to are represented in Figure 3 by coil Q wound on`v thestator. A rotating field is set up in the rotor la, Figure 3 by windingsnot shown. The angularposition of the rotor is dic-- tated by thecurrent in coil P. The phase angle between `the voltage set up in coil Qand the current in coil P is dictated by' the mechanical angle O betweenP and Q. In

Figure 3 I am'showing only single phase operatioirby coil P and Q; it isobvious however that polypliase circuits may be fed from similaradditional coils to Q spaced at the proper mechanical angle around thestator. Such additional coils are shown in Figures 4, 5 and 7 and theirfunctions described elsewhere in this specification. v

In the diagram Figure 4, the property of my power factor meter withauxiliary windings above set forth is shown as applied to measure voltamperes in a 3 phase load independent of power factor. The stator G androtor lc are the same as illustrated in Figure 2 with the rotor woundthe same as any 3 phase induction motor to produce a rotating field.

W represents any standard polyphase watt meter or watt hour meter inwhich C1 and C2 are the current coils and V1 and V? are the voltagecoils. Currents proportional to the load to be measured are takenthrough 'the current coils C1 and C2 preferably by means of currenttransformers T1`and T". VVindings in the stator slots 3 and 9, arrangedto function similar to coil P in Figure 3 are connected in series withtransformers T1 and coil C1 and windings in slots 5 and 11 are connectedin series with coil C2 and transformer T3. The two pairs of slots 3 9and 5--11 are located at an angleof 120 apart. .This is the samemechanical angle as the electrical angle between the currentscirculating. Transformer '1"2r conducts current through a winding` inslots l and 7 but this may be omitted if desired as the common returnfrom transformers Tl and T 3 has the same value b oth yin magnitude andphase position.

The action of these three currents in the stator G coupled with theaction of the voltage-excited winding on cause the rotor le ssY ias

' placed in phase position from the current in the windings of slots 3 9and 5 11 respectively, the direction of the phase displacement beingdifferent as it should be. This vis illustrated in Figure 5 in which Smrepresents a source of 3 phase supply ABC and. W represents a polyphasewatt meter con-' nected in the usual manner and showing the electricalangle between current B and voltage AB as O and between current G andvoltage AC as 30 in the opposite phase relation, that is, assuming a100% power factor.

Tt will thus be seen that vthe power factor meter with any standard wattmeter or watt hour meter with connections as illustrated in Figure 4will measure volt amperes, or volt ampere hours of a three phase circuitat any power factor, lagging or leading, input or output. 4

ln the diagram Figure 6 is shown the application of the method hereindescribed to a two phase circuit, the only difference between the twophase and three phase arrangement being the windings and connections. V

The stator G androtor 7c are the same as those describedffor athreephasey device.'

The current Vfrom the ltransformer T1 in` phase A is taken first throughthe current coil C1 of the watt meter and thence through the windings inthe slots 6, 2, 8 and l2 of the stator. The current from the transformerT2 in phase B is taken through the coil C2, of the watt lmeter andthence through the windings in the slots 3, 11, 5 and 9 of the stator.The rotor is voltage excited and` with these two currents circulatingthrough the stator in the manner Adescribed the rotor le will assume a.position dictated' by the lag or lead of the currents in transformers T1andT2 such that the magnetic flux due to' the combined rotor and statorwindings is the maximum. Y

The voltage coil V1 of the watt meter is yexcited from a winding laid`in slots 1 and 7 of the stator and the voltage coil V2 is eX- citedfrom the winding in the slots'4 and 10 consequent-ly the voltage ofthecoil V1 is at all times in phase with the currents circulating in s lots6, 2 and 8, l2 and the voltage ofthe coil V2 is in phase with thecurrent in the slots 3, 11 and 5,9 and the result. is registration ofvolt' amperes independent of the amount ,of lag 'or lead.`

From the foregoing "description it will'be evident that voltamperes'inasingle phase circuit may be measured by producing a suitablerotating iield'in the rotor [aand this :ncaa-sti may be accomplished'byproper well known methods of phase splitting of the exciting currents inthe rotor. F

In Figure 7 I sho-w the application of the i phase shifting functions ofthe power factor meter hereinbefore described in'connection with athermal demand meter. to enable the measuring of demand in volt amperesrat-her than in. watts as has been the practice.

Current Afrom the current transformer T1 of the three phase circuit ABCis led to the similar heaters H1 and H2 where it divides iiowing equallytherethroughl and through a winding in the slots 3 9 of the stator. Thewinding in slots 3 9 is tapped at its midpoint and the tap leadsdirectlyto the windng in the slots 2 8 which is connected with ransformer T. Thecurrents in the two 'ialves of the winding are equal and opposite exceptfor the influence ofthe voltage generated therein due to transformeraction, consequently the current from the trans'- former T1 iowing inthe winding in slots 3 9 will have no position determining effect on therotor 7c to causeI it to act as a power factor meter. This position'rdetermining effect-is obtained by the winding in slots Similarly, thecurrent Afrom the current transformer T2 is led to`similar heaters H3and H4 between which it divides equally and from thence passesthrough awinding irr the slots 5 11 which winding 120 electrical degrees from thewindings in slots The current is taken from the mid point of thewindingin the slots 5 11 and conducted through a winding in the slots 612. The winding` in slots 5 l1 will have "no position determiningeffect, this being supplied for this phase by the winding in slots 6 12.:The current from the transformer T1 after passing through the windingsin the slot's.3 9 and 2 8 current of the transformer T2 after passingthrough the windings in the slots 5 11y and so i' is combined 'with 'the6 12 and the resultant current` is conducted through aposition-determining winding arranged 1n the slots At l0 returningthence yto the transformers as shown. The voltage induced in thewindings in slots 3 9 is 30 from the phase position of the current in' Ithe slots 2 8. This voltage causes a current to flow in series throughthe two heaters H1 and Hand this voltage current combined with the loadcurrent from the transw former yT1 causes a difference in heat suppliedto the two heaters H1 and H2 to be always proportional to volt amperes.

Similarly the heaters H3 and H4 in the other phase will measure voltamperes in that phase and the sum of the two quantities gives a'measureof the total volt amperes in thel entire circuit ABC. i y

' It .is of course not new to use thermal watt meters for measuringdemandin watts but it is new toapply to such measuring means a method ofautomatic phase shifting for the purpose of measuring' demand in voltamperes. l lt is sometimes desirable to ascertain the approximate powerfactor at which the volt amperes of demand are taken and this can beeasily accomplished by providing indexes to be moved by the action ofthe power factor meter.

\ As indicated in Figure 8 an indicator arm R is attached to the rotorIt and a suitable scale Timarked in power factor or other desirablevalues is arranged' in the path of movement of this arm. Indexes U and Vare arranged upon the scale and as the ,rotor assumes various positions,depending upon the power factor ofthe circuit under measurement, eitherindex member will be moved along the scale so that .when areadingistaken the position of these indexes will be noted and they will indicatethe limits of the power factor betweenwhich the demand in volt ampereshas occurred. After reading,

these indexes may be moved into contact with the arm R to repeat theirindication.

The rotor of the power factor meter as' herein described is wound to setup a rotatfor the tendency to rotate. i found desirable to utilize amechanical corrective member such as described and the ing field, andunder certain conditions the action of this rotating field may causelosses in the stator windings which may induce an action partially thatof an induction` motor, consequently the proper functioning as a powerfactor meter will be somewhat impeded. In order toiovercome thiscondition of partial error,-I provide a helical spring W? having itsinner end secured to the shaft e of the rotor c and its outer end W2 isadjustably secured at any point in the stationary circular guide slot N.The value of the torque tending to rotate k as an induction motor willdepend on the resistance of the local short circuited circuits in thestator G and upon the voltage applied to the rotor 1c. Both of thesequantities are practically constant and the tension of the spring W14may be adjusted to compensate It may not be desired result may beachieved by'arranging the position determining windings sufficientlypowerful to overcome the induction motor torques set up. Such anarrangementy may notbe effective at low loads in overcoming thelinduction motor torque and the spring will then be necessary.

An important feature in designing a power factor meter tor .the purposedescribed 'is to provide a minimum current and losses in the windingsthat excite the irotor. Referring to the diagram Figure 2,

if there` is no current flowing from transformers T1y T2 'la all oftheexcitation required by th-e magnetic circuit is taken 'through the rotorwinding. ,When the currents in the transformers yare a maximum theresulting magnetic flux ,is produced by the joint action of; the rotorand stator windings. As has been described, with exciting currents inboth windings, the rotor 7c will assume such a position as will resultin the maximum magnetic flux.

It must not be assumed that the flux is materially increased by theaction of the stator windings assisting the rotor windings. If forinstance, it requires l0() ampereturns yto excite the rotor'k with agiven voltage applied to the windings of the lrotor and no excitation isapplied to` the'fstator and then assume that a current flows through thestator windingsso that 100 ampere turns are provided by the stator;I thevoltage applied to the rotor has not changed, consequently the fluxcutting the rotor windings cannot change materially. The existence of100 ampere turns' in the stator `will simply mean that the current takenby' the; voltageexcited winding of the rotor is reduced toy practicallyzero and the magnetic flux will be increased only to the extent of thevoltage drop through the resistance and leakage re-- actance of therotor circuit. :The counter l E. M. F. of the rotor must of. coursealways `be equal to the applied E. F. i If the counter' M. F. is made upof a large factor, due to the rotating flux, plus a small factor, due toresistance and magnetic leakage, it is obvious that a change inthe rotorcurrent can affect only the small factor due vto rot-or resistance andmagnetic leakage, lthe magnetic leakage being Athe magnetic iiux which'links only the rotor windings without also linking the stator windings.It

is important therefore that the design of the device be such that theresistance andleakage reactance voltages, due to the current A.

flowing in therotor, be aminimum.

The automatic feature herein described is very desirable but if theposition determining windings are omitted or prevented from functioningthe rotor may be operated manually,`similarly to the switch arm 'D shownin Figure 1, to shift the phase. When thus used the watt meters may beused at will as wattmeters, as reactive volt ampere meters or as metersreading volt-amperes correctly at certain specic power factors dependingon the angular position at which vthe rotor -is manually adjusted.

In the diagrams herein shown the voltages i in the rotor and stator arethe same but the stator. may be on one voltage andact las a voltagevtransformer by having lower voltage windings on the rotor or viceversa. i This will enable the use of a low voltage meter on a hightension current.

What 'I claim as my invention is 1. Means for measuring volt amperes,

comprising a power factor meter having current windings and voltagewindings relatively movable, a Watt meter, a secondary winding on saidpower factor meter connected with said watt meter, an indicator armattached to tlie movable element of said power factor' meter, astationary scale arranged in the path of movement of said arm, andmovable indexes arranged upon said scale and operatively engaged by saidarm.

2. Means for measuring volt yaniperes, comprising an A. C. circuit, 'apower factor meter having current and voltage windings separatelyconnected to the A. C. circuit, a secondary winding on said power factormeter, a watt meter connected with said Secondary Windings,'and anadjustable resistance medium connected with the rotor of said powerfactor meter adapted to countei'balance the induction motor action ofthe rotor.

8. lWeans for measuring volt ampres,` comprising an A. C. circuit, apower factor" meter having current and voltage windings separatelyconnected to the A, (l. circuit, a secondary winding on said powerfactor meter, a watt meter connected with said secondary windings, and ahelical spring having one end secured to the rotor and its other endadjustably secured to the stator of the power factor meter to vary4 thevalue of the torque tending to rotate the rotor ask I an inductionmotor.

LOUIS A.. PANE.

